Grill or Broil?

I was cooking swordfish with a friend last night, and her fish cookbook (James Peterson's Fish & Shellfish) makes the following observation:

Although grilling and broiling are similar techniques—in some parts of the United States the two words are used interchangeably—grilling is used here to mean cooking over, but not in contact with, the heat source. Broiling is cooking under the heat source.

Here's the question: Which parts of the United States? Perhaps the southeast which is really the region I don't know anyone from. Initially, we thought we couldn't think of any examples of people using "broil" to mean "grill" or vice versa, but Burger King does refer to its burgers as "flame broiled" when I would say they're grilled.